1) acording to some religions jesus was born on Dec. 25 some time far in the past, by the virgin Mary. could aliens have impregnated her and the bright star that the wisemen followed was a UFO?
First off, Jesus was born in July; the only reason Christmas is celebrated on the 25 of Dec. is because the Catholic church decided that they had to move it so that it would not be affiliated with a Pagan celebration on the same day. Why the couldn't move it to the following day...who knows. Anyway, Aliens could not have possibly have impregnated Mary and been the same thing that the wise men followed. The wisemen would have needed to follow the star for nine months--unless of course the UFOs just decided to stay there in the same geosynchronous orbit for these nine months until Jesus was born only to leave immediately after. However, I guess aliens could have impregnated Mary and the star was just a star (or beacon if you want to go with the alien thing), but if the aliens were smart enough to impregnate Mary without having sex with her or leaving any distinguishing characteristics of artificial insemination (such as a needle prick or a swolen anus from the anal probe), why just leave without any further examination. I honestly do not think that true logic (God inteded logic)--particularly the part of logic that says to finish what you started--differs from planet to planet.
2) Is there more than one universe, is it not possible our universe is simply a neutron on a atom partical of something much larger?
There cannot be more than one universe. Whatever scientist came up with the idea of multiple universes was really dumb because the word universe was created to signify the entire area of space. The only way another universe could exist, is if it were to be paralleled with this one; every atom densely compacted along side its equal and slightly out of phase to keep the objects within one from colliding with those in another.(cool huh)
3) could dinosaurs be our modern day ETs? could there have been lifeforms on this planet before the dinosaurs and they just simply packed up and left. did they kill off the dinosaurs? Could there be old ruins deep deep DEEP within our earth...?
Dinosaurs could possibly have been aliens--I have thought about this myself--but the more you think about it, the less likely. Dinosaurs tended to operate in herds like animals. If they were intelligent lifeforms they probably would have created big-ass tools and not segregated other species entirely (especially because they were mostly on one landmass). However, it is very possible that aliens could have killed them off and left without a trace because aliens would have to be smart enough to not leave their personal belongings. Furthermore, there is still a lot that has not been uncovered by archaeologists; they may one day discover a piece of alien material.
Hope that helps.